Means for indicating and/or recording unknown quantities



Sept. 16, 1941. M. J. JOHNSON MEANS FOR INDICATING AND/OR RECORDING UNKNOWN QUANTITIES Filed Oct. 17, 1936 NN. m MM Q fl k mu- Manfred J0 CYL INVENTOR f ns/J12, ATTQRNZ! Patented Sept. 16, 1941 UNITED STATES PATENT. OFFICE MEANS FOR INDICATING AND/a unconn- ING UNKNOWN QUANTITIES Manfred J. Johnson, Naugatnck, Conn., assignor of one-half to The Lewis Engineering Company,

N augatuck, Conn.

Application October 17, 1936, Serial No. 106,085

13 Claims shaded-pole A. C, induction motor for adjusting the slide wire, pointer, ruling pen, or other devices of a potentiometer circuit, said reversible motor being controlled in response to deflection of the needle of a galvanometer in the potentiometer circuit.

According to my said invention, in one of its embodiments, the anodes of a pair of thermionic devices are coupled to the shading coils of the induction motor by a pair of transformers, one for each thermionic device, and the grids of said devices are controlled by means including a pair of contacts on a rotating drum adapted to cooperate with a contact of the galvanometer needle.

Now, I have found that it is possible to concoupling transformer connecting the plate of the device of the shading coils of the motor, and using means connected with the shading coils of the motor and actuated automatically, for selecting the proper direction of rotation of the motor.

In an embodiment of this new system, the selection of the proper set of shading coils, of the motor, to be loaded for causing rotation thereof and adjustment of the slide wire, is accomplished by a selecting switch in the shading coil circuits, operating in synchronism with control contacts associated with the deflection device. A feature of this embodiment is that the selecting switch is operated so that contact is made and broken during periods when no current flows in the shading coil circuit, and therefore no sparking whatever is present in said switch.

Although the embodiment of the invention illustrated herein shows the control system as including drum-carried contacts coacting with a galvanometer needle, and a selecting shadingcoil switch automatically operative with said to this specific construction, and the protection contemplated is to be more properly taken in connection with the appended claims.

Other features and advantages will hereinafter appear.

The accompanying drawing shows diagrammatically the present improved potentiometer system.

Referring to the system diagrammatically illustrated in this figure, the potentiometer circuit, used with a thermocouple which varies according to a change of conditions, includes a primary source of energy in the form of a battery III which is connected by a wire H to a variable calibrating resistance l2, and by a wire l3 to one end of aslide wire l4 mounted on the periphery of a stationary disk IS. The other end of the slide wire I4 is connected by a wire IE to a resistor l I which in turn is connected by a wire l8 to the other end of the calibrating resistance l2. A resistor I9 is shunted across the slide wire H for the purpose of reducing the voltage drop across the latter. A complete circuit is thus formed through the slide wire I4 and shunted resistance IS, the resistor ll, the calibrating resistance l2, and the battery l0, and current flows through this circuit as a result.

A galvanometer 20 is connected by a wire 2| to one end of the slide wire I, and by a Wire 22 through a switch 23 to a thermocouple 24 which is in turn connected by a wire 25 to a slider 26 which moves around the disk I5 and contacts with the slide wire I 4. Thus the galvanometer 20 and the thermocouple 24 are shunted across a portion of the slide wire 14, as determined by the position of the slider 26, and it is possible, by adjustment of said slider and the calibrating resistance l2, to secure a balanced condition such that no deflection of the galvanometer results. For the purpose of checking the potential drop across the slide wire ll of the potentiometer circuit just described, a standard cell 21 is connected by a wire 28 to the wire 18, and by a wire 29 to an alternative contact of the switch 23. It will be readily understood that, for a condition of no deflection oi the galvanometer 20, the slider 28 may have various positions, these. positions corresponding to various temperatures to which the thermocouple 2! is subjected. A pointer 30 is carried on a shaft 3| which is attached to the slider 26, and therefore the various positions of the pointer 30 can be used as an indication of the various temperatures of the thermocouple 24.

I have disclosed in my application Serial No.

contacts, it is not desired to limit the invention 35,151, filed August '7, 1935, the use of a reversible shaded-pole alternating-current motor controlled by means including thermionic devices, which in turn are under the control of the galvanometer, the motor being employed to move the slider of the potentiometer system.

posed shading coils 36, 36 also connected in series.

Because of the A. C. energization of the motor field, the shading coils 35, 35 and 36, 36 will have alternating voltages induced in them, and said coils are so disposed on the pole pieces of the motor that loading or short-circuiting of one set of shading coils will cause rotation of the motor in one direction, and loading or shortcircuiting of the other set of shading coils will cause rotation of the motor in the other direction.

In my above-identified application, motor control is effected by a pair of thermionic devices, these being coupled to the shading coils of the motor by transformers. The thermionic devices are in turn controlled according to deflection of the galvanometer needle by a contact system including drum-carried contacts adapted to engage the galvanometer needle, and this control operates so that deflection of the needle in one direction causes functioning of one of the thermionic tubes, to operate the motor in one direction, and deflection, of the needle in the opposite direction causes functioning of the other of the thermionic tubes, to operate the motor in the opposite direction. 7

According to the present invention, however, the alternating current motor 32 is operated by a novel control, which, in the embodiment shown,

comprises a system including but a single thermionic tube, and including novel contact and selecting means, associated with the tube. This contact and selecting means is shown as including a pair of staggered drum-carried contacts adapted to engage the galvanometer needle,.and including an automatically operated selecting switch in the motor shading coil circuit, thislatter automatically switching the impulses from the thermionic tube to the proper shading coils 53 of a supply transformer 54, .the center tap of said winding being connected by a wire 55 to the remaining end of the secondary coil 50 of the transformer 40. The supply transformer 54 has a primary winding 56 connected with supply wires 51 and 58 of a suitable alternating current supply.

It will be seen that when the switch 43 is closed in either position, the transformer 46 will be energized by the induced voltage'of one set of shading coils, and the secondary 59 will impress an alternating voltage on the anode of the tube 48. This anode voltage is of a value in con- .formity with the operating requirements of the tube, and preferably the transformer 46 steps up the voltage of the shading coils to meet this value. As in my copending application above referred to, the thermionic system for controlling rotation of the motor 32 is caused to respond to deflection of the galvanometer 26 by means of electrical contacts associated with said galvanometer; however, the contact means as provided in the embodiment shown herein is novel, and difl'erent in particulars from the previous means referred to, and said means is adapted to cofunction with automatic operation of the selecting switch 43.

As shown, the galvanometer 26 has a needle 59 which is periodically depressed in its various positions by a bail 66 actuated bya double wing cam and a follower 6| and 62 respectively, the cam being carried on a shaft 63 provided with a worm'gear 54 operated by a worm'65 from an electric motor 66. The cam 6| isadapted to cause the bail 66 to depress the needle 59 twice during each revolution of the cam. The shaft of the motor, and being actuated periodically with rotation of the drum.

Referring to the drawing, oneend of the series connected coils 35, 35 is joined by means of a wire 31 to one end of the series connected coils 36, 3'6 and this junctureis connected by a wire 38 to the primary winding 39 of a plate circuit transformer 46. The other end of the primary 39 is connected by a wire 4| to the resilient throw blade 2 of a single pole double throw electric switch 43. This switch has a pair of bladeengaging contacts 44 and 45, the contact 44 being connected by a wire end of the series connected shading coils 36, 36

and the latter contact being connected by a wire 41 to the remaining end of the series connected shading coils 35, 35. 1

.Since the field coil 34 of the motor 32 is constantly a e will be induced in each set of shading coils thereof, and either set may beloaded, accordin to the position of the switch blade-42. of a suitable impulse in the winding 39 of the transformer 46, to cause rotation of the motor in one direction or theother.

46 to the remainin energized with alternating current, voltby means 63 carries a drum 6 I of insulating material, on which is mounted a pair of substantially triangular-shaped contacts 68 and 69 at oppositesides of the drum, and extending from opposite ends thereof toward the longitudinal center. The contacts 69 and 69 are connected with metal end-plates l0 and H respectively which serve as collector rings for' brushes 12 joined together by a wire 13, which wire is in turn connected by a wire 14 to the grid of the thermionic device 48. Thus the brushes 12 electrically connect the contacts 66 and 69 together, and connect these to the grid of the device 48.

The contacts 69 and 69 are so disposed on the drum 61, and the cam 6| is so shaped and positioned on the shaft 63 that, when the galvanometer needle 59 is depressed by the bail 66, said needle will frictionally engage,as the drum 61 rotates, either contact 69 or 69, depending on whether the needle is deflected to either the right or to the left. Also, if the needle is in zero or in non-deflected position, it will, when depressed, engage the drum 6'! at its center just beyond the pointed ends of thecontacts 68 and 69, and will not engage either contact.

An anvil 15 is disposed directly below the needle 59 so that when the latter is depressed it will engage and contact with the anvil,. and the latteris connected by a wire 16 through a grid resistor 11 to a grid coil 16 of the transformer 54. The coil [8 "has a center tap connected by a wire 19 with the center tap of-the filament coil 53, and the remaining end of the' grid coil is connected through a grid resistor 83 to the wire 14 leading to the grid of the thermionic tube 48.

It will be seen that when the needle 53 of the 6 nating voltage from the grid coil 18, through the 10 resistor 80. According to this invention, this voltage is synchronized with the alternating voltage applied to the plate or anode, but is in phase I opposition to said voltage.- To accomplish this,

the field coil 34 of the motor 32 is connected to the supply wires 51 and 58, and this connection is such that the induced voltages of either set of shading coils of the motor will, when the switch 43 is in closed position, energize the transformer 46 so that the secondary coil 58 thereof impresses the desired voltage, of opposite polarity to that of the grid, on the plate of the tube 43.

When the needle 53 of the galvanometer is not touching either contact 68 or 63, no current will flow in the plate circuit of the thermionic device 48 since, during the intervals that the plate of said device is positive, the negative bias provided on the grid is suflicient to keep the plate current 'substantiallyzero. Of course, during the inter-" vals that the grid is positive due to alternating of the supply voltage, the plate will be negative, so that no plate current can flow. for this condition.

Should the galvanometer remain in zero or.

non-deflecting position, the motor 32 will not be 35 caused to move at all, since no current will flow in the plate circuit of the thermionic system to load the shading coils of the motor. However, should the galvanometer needle deflect in either one direction or the other, it will, when depressed periodically by the ball 68, connect one or the other of the contacts 63 or 63 through the anvil 75 to the resistor 11. This resistor is preferably of a value equal to that of the resistor 83 so that,

as a consequence of the contact caused by the galvanometer needle, the voltage on the grid of the tube 48 will be reduced to substantially zero. This will cause, during intervals of positive polarity of the plate, a current to flow in the plate circuit, thereby loading, as determined by the 50 position of the switch 43, a set of shading coils so as to cause rotation ofthe motor 32.

Thus deflection of the galvanometer needle 53 can, depending on the position of the switch 43, load either set of shading coils to cause rota- 55 tion of the motor 32 in either direction.

By the present invention the switch 43 is actuated automatically with turning of the drum 61 by means of a cam 83 carried on the drum shaft 63 and engaging an insulating 'shoe 34 carried 3 by the switch blade 42, said blade being normally biased toward the contact 44. The cam 83 is so shaped that the switch blade 42 will engage the contact 45 of; the switch whenever the contact 63 carried by the drum is uppermost and in posi-. 65

tion to be engaged by the needle 63, and the blade 42 will engage the contact 44 of the switch when the contact 63 is uppermost on the drum and in position to be engaged by the galvanometer needle; intermediate these positions of the contacts the blade 42 will be held out of engagement with either of its associated contacts. Thus,

should the galvanometer needle deflect and be depressed so as'to engage the contact 68 of the current carried by be engaging the contact connected with the shading coils 36, 36.

Preferably the cam 33 and switch 43 are so arranged that the latter closes a shading coil circuit before contact can be established to either of the drum contacts 68 or 63, and opens the shading coil circuit after this engagement with either of the drum contacts by theneedle 53 is broken. Thus, there will be positively no arcing at the contacts of the switch 43, since contact is made and broken and during the periods when the current through the shading coils is extremely low, as no plate current can flow unless either of. the drum contacts is engaged by the galvanometer needle.

The motor 66 is connected to the common source of current supply, as by wires 35 and 86. and preferably the speed of this motor is such that the drum 6! will turn sufliciently slowly, relatively to the frequency of the A. C. energization of the system, that several alternations of current will take place during a period of contact between the needle 53 and either contact 68 or 63 when the galvanometer is deflecting.

The potentiometer system as just described is therefore self-balancing, and the pointer 33 connected with the slider 26 will indicate the temperature of the thermocouple 24. Should there be any change in the temperature to which this thermocouple is subjected, the change in e. m. f. of the couple will unbalance the potentiometer circuit and cause deflection of thegalvanometer 23. This deflection will result in periodic contact of the needle 53 with one of the drum contacts 68, 63, and consequently will result in rotation of the motor 32 and adjustment of the slider 26 so as to bring the potentiometer circuit again in balance, the new position of the slider and the pointer 30 indicating the new temperature. When this condition is reached, the galvanometerwill again remain in non-deflecting position, and the control will be inoperative until a change in temperature is again experienced by the thermocouple 24.

It will be noted that no arcing occurs at the contacts of the switch 43 since connections are made and broken for no current conditions of the shading coil circuits. Also, no arcing will occur at the galvanometer contacts, since the these contacts is extremely small. Also, the potentiometer and control 11- lustrated herein is sensitive and quick acting, since several impulses will be transmitted to the shading coils during any one period of engagement of the galvanometer needle 53 with a drum contact.

Variations and modifications may be made within the scope of this of the improvements may be used without others.

I claim: v

1. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including an electro-responsive means operative in reverse directions; control circuits, for controlling.- the direction of operation of said means;

electron discharge system connected with drum and cause functioning of the thermionic said control circuits, for causing operation of the invention and portions.

electro-responsive means; a galvanometer'in ciredit with the slide wire and having a deflectable member; means including contacts engageable by the deflectable member for controlling the functioning of the electron discharge system in response to deflection of said deflectable member in accordance with a change in condition in the slide wire circuit; and circuit control means connected in said control circuits, and automatically operative in timed relation with the last-mentioned means, for causing the electron discharge system to operate the electro-responsive means in one direction or the other, depending on the direction of deflection of the deflectable member.

2. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including an electro-responsive means operative in reverse directions; control circuits; for controlling the direction of operation of said means;

an electron discharge system connected with said control circuits, for causing operation of the electro responsive means; a galvanometer connected in circuit with the slide wire; means including contacts cooperable with the deflectable member for controlling the functioning of the electron discharge system in response to deflectem to operate the electro-responsive means in one direction or the other, depending on the direction of deflection of the galvanometer, so as to adjust the slide wire.

3. The invention as defined in claim 1, in

which the 'electro-responsive means comprises an A. C. motor having a continuously excitedfield and oppositely disposed wire wound shading coils, in which the said control circuits are connected to the shading coils of the motor, and in which the circuit control means includes a switch for selectively connecting the shading coils to the electron discharge system.

-4. In a potentiometer system, an adjustable slide wire;-means for adjusting the slide wire, including a reversible A. C. motor having a continuously excited field and oppositely disposed wire wound shading coils; a deflectable member having a normal or zero position; means in said slide wire circuit for moving the deflectable member to either side of the zero position in accordance with the magnitude of a condition; a thermionic device; a circuit controlled by the off zero movements of the deflectable member and connected with the grid of the thermionic device, including means for polarizing said grid; means coupling the wire wound shading coils of the motor to the plate of the thermionic device, said means including a transformer whereby voltages induced in the. shading coils 60 ergizing said circuit to cause rotation of the motor; and means for automatically operating the shading coil connecting means concurrently with the grid depolarizing means connected to the deflectable member.

5. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including a reversible A. C. motor having a continuously excited field and oppositely disposed wire wound shading coils; an electron discharge device; means for coupling the electron discharge device to the shading coils of the motor; auto- 5 matic switch means in the shading coils circuit for alternately connecting each coil; a galvanometer connected to the slide wire; and means for causing periodic functioning of the discharge device in-response to deflection of the galvanoml0 eter, the periods of functioning due to deflection in one direction corresponding to the periods of connection of one shading coil, and the periods of .function due to. deflection in the other direction corresponding to the periods of connection of the other shading coil.

said slide wire circuit including a deflectable membermovable in accordance with the magniture of a condition in said circuit; control circuits including said deflectable member for rendering said means operable and for controlling the direction or operation of said means; an electron discharge system, including a three element thermionic tube for causing operation of the electro-responsive means, said tube having its anode connected with the control circuits; means for impressing a voltage on the grid of the thermionic tube, including contacts engageable by the deflectable member and means for altering said grid voltage in response to the closing of the contacts due to deflection of; the deflectable member to cause operation of the electro-responsive means; and circuit selecting means connected in said control, circuits, and automatically operative with the last-mentioned means, for

causing the electron discharge system to operate 40 the electro-responsive means in one direction or the other depending on the direction of deflection of the deflectable member.

7. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire,

' including an electro-responsive means operative in reverse directions; control circuits, for con-.

trolling the direction'of operation of said means;

a galvanometer in circuit with the slide wire andv having a deflectable member; switch means actuated by the deflectable member, and connected in said control circuits, for periodically closing and opening a circuit according to a given constant period when the said member deflects in one direction, and. for periodically closing and 5 opening the circuit according to a similar period when the member deflects in the other direction, said periods being in constant phase opposition; and means connected with said switch means and control circuits, and automatically actuated means to operate in the reverse direction when the member deflects in the other direction, in which the switch means includes a contact directionally movable by the deflectable member, a pair of contacts for engagement .with the first 7 contact, and-means for periodically alternately bringing the contacts of said pair into the field- 0! action of the directionally movable contact. 8. In a potentiometer system,'an adjustable slide wire; means for adjusting the slide wire including a normally inactivereversible A. C.

motor having a continuously excited field and oppositely disposed wire wound shading coils; an electron discharge device; means for coupling the electron discharge device to the shading coils of the motor; automatic switch means in the circuit for the shading coils for alternately connecting each coil to the electric discharge device; a galvanometer in circuit with the slide wire and having a deflectable member; and means for causing periodic functioning of the discharge device in response to deflection of the deflectable member, the periods of functioning due to the deflection in one direction corresponding to the periods of connection of one shading coil, and the periods of function due to deflection in the other direction corresponding to periods of connection of the other shading coil.

9. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including a reversible motor; a switch in the circuit of the motor for reversing the same; a relay for closing the circuit to the motor; means in said slide wire circuit including a deflectable member movable from a normal position in accordance with the magnitude of a condition in said circuit; a drum having contacts in the relay circuit angularly displaced on its surface to engage the deflectable member in the deflected position; means for periodically moving the deflecting member so that it may close the circuit to the relay; and means for rotating the drum and operating the switch in timed relation to thereby control thedirection of rotation of the motor in accordance with the position of the deflectable member. I

10. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire including a normally inactive reversible A. C. motor having a continuously excited field and a pair of oppositely disposed wire wound shading coils; a relay and selector switch-connected in the circuit with the shading coils; means in said slide wire circuit including a deflectable member movable from a normal position in accordance with changes in magnitude of a condition in said circuit; a drum having contacts in the relay circuit angularly spaced on its surface to engage the deflectable member in deflected position; means for periodically moving the deflecting member so that it may close the circuit to the relay; and means for rotating the drum and operating the switch in timed relation to thereby control the direction of rotation of'the motor in accordance with the position or.v the deflectable member. i v

11. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, in-

cluding anelectro-responsive means operative in reverse directions; control circuits. for controlling the direction of operation of said means; an electron discharge system connectedwithsaid control circuits for causing operation of the electroresponsive means; 'means in said slide wire circuit including a deflectable member movable from a normal position in accordance with the magnitude of a condition in said circuit; means including normally open switch contacts cooperative with the deflecting member for controlling the functioning of the electron discharge system in response to deflection of said deflectable member; means for closing the switch contacts periodically during deflection of the deflectable member in either direction; andcircuit control means connected in said control circuits and automatically operative in timed relation with said lastnamed means for causing the electron discharge system to operate the electro-responsive means in one direction or the other, depending upon the direction of deflection of the deflectable member.

12. In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including an electro-responsive means operative in reverse directions; control circuits for controlling the direction of operation of said means; an electron discharge system connected with said control circuits for causing operation of the electro-responsive means; means in said slide wire circuit including a deflectable member movable from a normal position in accordance with the magnitude of a condition in saidcircuit; means including a switch having contacts engageable by the deflectable member for controlling the functioning of the electron discharge system in response to deflection of said deflectable-member; means for closing and opening the switch periodically during deflection of the deflectable member; and circuit control means including a periodically operated switch connected in said control circuits and automatically operative in timed relation with said first-mentioned switch for causing the electron discharge system to operate the electro-responsive means in one direction or the other, depending on the direction of deflection of the deflectable member until the slide wire has been adjusted.

13, In a potentiometer system, an adjustable slide wire; means for adjusting the slide wire, including an electro-responsive means operative in reverse directions; control circuits controlling the direction of operation of said means; an electron discharge device; means connecting said device with the control circuits for operation of the electro-responsive means by the device; a galvanometer in circuitwith the slide wire and having a deflectable member; means including switch means having periodically moving contacts engageable by the deflectable member and operable in response to the deflection of said member for controlling the functioning of the electron discharge device; and circuit control means including aselecting switch operatively connected to operate in timed relation with said 

